Driving tool

ABSTRACT

A driving tool includes a motor, a flywheel, a driver and a control part. The driver is disposed to face an outer periphery of the flywheel and configured to perform a driving operation of driving the fastener into the workpiece by moving along an operation line, by rotational energy transmitted from the flywheel. The control part is configured to control driving of the motor. The control part is configured to set rotation speed of the motor based on first information and second information. The first information corresponds to rotational energy of the flywheel before the driving operation of the driver. The second information corresponds to rotational energy of the flywheel after the driving operation of the driver.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Japanese patent applicationNo. 2018-145459 filed on Aug. 1, 2018, the contents of which are fullyincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a driving tool that is configured todrive a fastener into a workpiece with a driver.

BACKGROUND ART

A driving tool is known which is configured to drive a fastener such asa nail into a workpiece by linearly moving a driver. For example, U.S.Pat. No. 7,646,157 discloses a driving tool which includes a powersource including a motor and a flywheel, a driver, a follower forfrictionally engaging the driver with the flywheel, an actuator fordriving the follower, and a control part for selectively actuating themotor and the actuator. In this driving tool, the control part isconfigured to control supply of electric power to the power source suchthat the flywheel rotates at a specified speed, based on rotation speedof one element of the power source which is detected by a speed sensor.

SUMMARY

Kinetic energy (rotational energy) stored in the flywheel by rotation isproportional to the moment of inertial and to the square of the angularvelocity of the flywheel. Therefore, when the rotation speed of theflywheel is controlled to a constant speed like in the driving tool ofU.S. Pat. No. 7,646,157, the kinetic energy of the flywheel also becomesconstant. On the other hand, kinetic energy required for the driver todrive a fastener in an optimum state may vary, depending on the fastenerand a workpiece into which the fastener is driven. Therefore, in thedriving tool of U.S. Pat. No. 7,646,157, excessive output orinsufficient driving may be caused.

Accordingly, it is an object of the present disclosure to provide adriving tool which is capable of properly controlling rotational energyfor driving a fastener.

According to one aspect of the present disclosure, a driving tool isprovided which is configured to eject a fastener from an outlet to drivethe fastener into a workpiece. This driving tool includes a motor, aflywheel, a driver and a control part.

The flywheel is configured to be rotationally driven by the motor. Thedriver is disposed to face an outer periphery of the flywheel, andconfigured to perform a driving operation by rotational energytransmitted from the flywheel. The driving operation refers to anoperation of driving the fastener into the workpiece by moving along anoperation line. The control part is configured to control driving of themotor. Further, the control part is configured to set rotation speed ofthe motor based on first information and second information. The firstinformation refers to information which corresponds to rotational energyof the flywheel before the driving operation of the driver, and thesecond information refers to information which corresponds to rotationalenergy of the flywheel after the driving operation of the driver.

It is noted that the first and second information may be the rotationalenergy of the flywheel itself or a physical quantity having apredetermined correlation with the rotational energy of the flywheel.Examples of the physical quantity may include rotation speed of themotor and rotation speed of the flywheel.

In one aspect of the present disclosure, the control part may beconfigured to set the rotation speed of the motor with reference tocorrespondences between the first information, the second informationand the rotation speed of the motor which are preset and stored in astorage part. The correspondences may be typically embodied by a tableor a database in which the first information, the second information andthe rotation speed are associated with each other and stored.

In one aspect of the present disclosure, the first information, thesecond information and the rotation speed of the motor may be associatedwith each other and stored in a table in advance, and the table may bestored in the storage part. Further, the control part may be configuredto set the rotation speed with reference to the table.

In one aspect of the present disclosure, the driving tool may furtherinclude a first sensor configured to detect rotation speed of the motoror the flywheel. In this case, the first information may be rotationspeed of the motor or the flywheel which is detected by the first sensorbefore the driving operation, and the second information may be rotationspeed of the motor or the flywheel which is detected by the first sensorafter the driving operation. It is noted that the first sensor maydirectly or indirectly detect the rotation speed of the motor or theflywheel.

In one aspect of the present disclosure, the motor may be a brushlessmotor. Further, the first sensor may include a Hall sensor which isconfigured to detect a rotation position of the motor.

In one aspect of the present disclosure, the control part may beconfigured to set the rotation speed of the motor to a maximum valuewithin a settable range in a case where the rotation speed of the motoror the flywheel which is detected after the driving operation is smallerthan a specified threshold.

In one aspect of the present disclosure, the control part may beconfigured to set the rotation speed of the motor to a maximum valuewithin a settable range in a case where a specified time elapses withouta next driving operation being performed after a driving operation.

In one aspect of the present disclosure, the driving tool may furtherinclude a second sensor which is configured to detect informationcorresponding to movement of the driving tool which is caused by thedriving operation. The control part may be configured to set therotation speed of the motor based on a detection result of the secondsensor.

In one aspect of the present disclosure, the second sensor may beprovided in a tool body which houses at least the motor and theflywheel, or in a handle connected to the tool body.

In one aspect of the present disclosure, the second sensor may be anacceleration sensor. The control part may be configured to set therotation speed of the motor to a maximum value within a settable rangein a case where the acceleration exceeds a specified threshold.

In one aspect of the present disclosure, the driving tool may furtherinclude an indication part which is configured to indicate informationrelating to a condition of driving the motor by the controller.

In one aspect of the present disclosure, the driving tool may furtherinclude a battery mounting part which is configured to removably receivea rechargeable battery.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory drawing for schematically showing an overallstructure of a nailing machine when a driver is placed in an initialposition.

FIG. 2 is a partial, enlarged view of FIG. 1.

FIG. 3 is a perspective view of the driver when viewed from above.

FIG. 4 is an explanatory drawing for schematically showing the driverplaced in a driving position.

FIG. 5 is a perspective view of a flywheel, a ring member, a holdingmechanism and a pressing roller when the driver is placed in the initialposition.

FIG. 6 is a sectional view taken along line VI-VI in FIG. 2.

FIG. 7 is a block diagram showing an electrical configuration of thenailing machine.

FIG. 8 is a table showing correspondences between rotation speed of amotor before driving operation, a range of the rotation speed of themotor after driving operation and the rotation speed of the motor forthe next driving operation.

FIG. 9 is a flowchart of driving control processing which is executed bya CPU.

FIG. 10 is a sequel to FIG. 9, showing the flowchart of the drivingcontrol processing.

FIG. 11 is an explanatory drawing for illustrating the driver placed ina transmitting position and a driver-driving mechanism.

FIG. 12 is a sectional view taken along line XII-XII in FIG. 11.

FIG. 13 is an explanatory drawing for illustrating the driver placed ina striking position and the driver-driving mechanism.

FIG. 14 is an explanatory drawing for illustrating a specificapplication of the driving control processing.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An embodiment is now described with reference to the drawings. In thepresent embodiment, a nailing machine 1 is described as an example of adriving tool. The nailing machine 1 is a tool which is capable ofdriving a nail 101, which is an example of a fastener, into a workpiece(such as wood) 100 by linearly driving out the nail 101.

First, the general structure of the nailing machine 1 is described withreference to FIG. 1. As shown in FIG. 1, an outer shell of the nailingmachine 1 is mainly formed by a tool body 10, a handle 14 and a magazine17.

The tool body 10 includes a body housing 11 and a nose part 12. The bodyhousing 11 houses a motor 2, a driver 3 and a driver-driving mechanism400. The driver 3 is disposed to be movable along a specified operationline L. The driver-driving mechanism 400 is configured to drive out thenail 101 from the nailing machine 1 by linearly moving the driver 3along the operation line L. The nose part 12 is connected to one end ofthe body housing 11 in an extending direction of the operation line L(hereinafter simply referred to as an operation-line-L direction). Thenose part 12 has an outlet 123, through which the nail 101 is drivenout, at the other end portion which is on the side opposite to the bodyhousing 11. Further, a contact arm 13 is disposed on the nose part 12 soas to be movable in the operation-line-L direction. A contact arm switch131 (see FIG. 7) is disposed within the body housing 11. The contact armswitch 131 is configured to be normally held in an off-state and to beturned on when the contact arm 13 is pressed.

The handle 14 extends in a direction crossing the operation line L, froma central portion of the body housing 11 in the operation-line-Ldirection. The handle 14 is configured to be held by a user. A trigger140, which is configured to be depressed (pulled) by a user, is providedin a base end portion (an end portion connected to the body housing 11)of the handle 14. A trigger switch 141 is disposed within the handle 14.The trigger switch 141 is configured to be normally held in an off-stateand to be turned on when the trigger 140 is depressed. Further, abattery mounting part 15 having terminals is provided on a leading endportion (an end portion opposite to the base end portion) of the handle13. A rechargeable battery 19 may be removably mounted to the batterymounting part 15.

The magazine 17 is configured to be loaded with a plurality of nails 101and mounted to the nose part 12. The nails 101 loaded in the magazine 17may be fed one by one onto a travel path of the driver 3 by anail-feeding mechanism (not shown). The structure of the magazine 17 iswell known and therefore its description is omitted.

In the present embodiment, the nailing machine 1 is configured to startan operation of driving the nail 101 into the workpiece 100 with thedriver 3 (hereinafter referred to as a driving operation) when both thecontact arm switch 131 and the trigger switch 141 are turned on by auser. In other words, the driving operation is performed in response touser's operations of pressing the contact arm 13 against the workpiece100 and depressing the trigger 140. The order of performing these twooperations is not particularly limited.

The detailed structure of the nailing machine 1 is now described. In thefollowing description, for convenience sake, the operation-line-Ldirection (right-left direction in FIG. 1) is defined as a front-reardirection of the nailing machine 1, and in the front-rear direction, theoutlet 123 side (right side as viewed in FIG. 1) is defined as a frontside of the nailing machine 1, while its opposite side (left side asviewed in FIG. 1) is defined as a rear side. Further, a direction(up-down direction as viewed in FIG. 1) which is orthogonal to theoperation-line-L direction and which corresponds to the extendingdirection of the handle 14 is defined as an up-down direction of thenailing machine 1, and in the up-down direction, the side of the baseend portion (upper side as viewed in FIG. 1) of the handle 14 is definedas an upper side, while the side of the leading end portion (lower sideas viewed in FIG. 1) of the handle 14 is defined as a lower side.Further, a direction which is orthogonal to the front-rear direction andto the up-down direction is defined as a right-left direction.

First, the internal configuration of the tool body 10 is described.

The internal configuration of the body housing 11 is first described. Asshown in FIG. 2, the motor 2, the driver 3, the driver-driving mechanism400 and an acceleration sensor 115 are disposed within the body housing11. These structures are now described in this order.

As shown in FIG. 2, the motor 2 is housed in a lower rear portion of thebody housing 11. Further, the motor 2 is disposed such that a rotationaxis of an output shaft (not shown) extends in the right-left direction.In the present embodiment, a brushless direct current (DC) motor isemployed as the motor 2. A pulley 21, which is configured to rotatetogether with the output shaft, is connected to the output shaft of themotor 2. In the present embodiment, driving of the motor 2 is controlledby a controller 18 (see FIG. 1), which will be described in detaillater.

As shown in FIG. 3, the driver 3 is an elongate member formed to besymmetrical in the right-left direction with respect to its longitudinalaxis. The driver 3 includes a body 30, a striking part 31 and a pair ofarm parts 35. The body 30 is a portion which has a generally rectangularplate-like shape as a whole. The striking part 31 is a portion which hasa smaller width than the body 30 in the right-left direction and extendsforward from a front end of the body 30. The arm parts 35 are portionswhich protrude to the right and left from a rear portion of the body 30.

The body 30 is a portion which is configured to be pressed by pressingrollers 83 (see FIG. 2), which will be described later, and to befrictionally engaged with ring members 5 (see FIG. 2). The body 30includes a pair of roller-abutting parts 301, a lever-abutting part 305and a pair of ring-engagement parts 306, which are described below inthis order.

The roller-abutting parts 301 are integrally formed with the body 30,protruding upward from an upper surface of the body 30 and extending inthe front-rear direction along right and left edges of the body 30. Asurface formed on a protruding end (upper end) of each roller-abuttingpart 301 is formed as an abutting surface to abut on an outer peripheralsurface of the pressing roller 83. A front end portion theroller-abutting part 301 is formed as an inclined part 302 which has aheight (thickness in the up-down direction) gradually increasing towardthe rear. On the other hand, a portion of the roller-abutting part 301which extends rearward from the inclined part 302 has a constant height.The lever-abutting part 305 is formed to protrude upward from the uppersurface of the body 30 and extends in the right-left direction so as toconnect the right and left roller-abutting parts 301 in a rear portionof the body 30. The lever-abutting part 305 is a portion on which apush-out lever 711 to be described later may abut from the rear.

The ring-engagement parts 306 are integrally formed with the body 30,protruding downward from a lower surface of the body 30 and extending inthe front-rear direction along the right and left edges of the body 30.A front end portion of each of the ring-engagement part 306 is formed asan inclined part 307 which has a height (thickness in the up-downdirection) gradually increasing toward the rear. The ring-engagementparts 306 have respective engagement grooves 308 configured to engagewith respective outer peripheral engagement parts 51 of two ring members5, which will be described later. Each of the engagement grooves 308 isrecessed upward from the protruding end of the ring-engagement part 306and extends over the whole length of the ring-engagement part 306 in thefront-rear direction. The engagement groove 308 is formed to have awidth in the right-left direction decreasing toward the top (in otherwords, such that wall surfaces of the ring-engagement part 306 in theright-left direction which define the engagement groove 308 come closerto each other toward the top) (see FIG. 6). Engagement between thedriver 3 and the ring member 5 will be described in detail later.

A rear end 32 of the body 30 defines a rear end of the driver 3. A frontend 310 of the striking part 31 defines a front end of the driver 3. Thefront end 310 is a portion which is configured to strike a head of thenail 101 (see FIG. 1) to drive out the nail 101 forward into theworkpiece 100.

The arm parts 35 protrude to the left and right from the body 30.Although not described in detail and shown, the arm parts 35 are eachconnected to a return mechanism disposed within the body housing 11, bya connecting member. The return mechanism is configured to return thedriver 3 to an initial position after the nail 101 is driven out. In thenailing machine 1 of the present embodiment, any known structure may beadopted as the return mechanism. For example, the return mechanism maybe configured to return the driver 3, which has been moved forward to adriving position, to the initial position along the operation line L byan elastic force of an elastic member (such as a compression coil springor torsion coil spring) via the connecting member.

The driver 3 having the above-described structure is disposed such thatits longitudinal axis extends in the front-rear direction of the nailingmachine 1, along the operation line L. Further, the driver 3 is held tobe movable along the operation line L (in other words, in the front-reardirection of the nailing machine 1 or in the longitudinal direction ofthe driver 3).

The initial position and the driving position of the driver 3 are nowdescribed with reference to FIGS. 1 and 4. The initial position is aposition where the driver 3 is held in a state that the driver-drivingmechanism 400 is not actuated (hereinafter referred to as initialstate). In the present embodiment, as shown in FIG. 1, the initialposition of the driver 3 is set to a position where the rear end 32 ofthe driver 3 abuts on a rear stopper part 118 fixed within a rear endportion of the body housing 11. The driving position is a position wherethe driver 3, which is moved forward by the driver-driving mechanism400, drives the nail 101 into a workpiece. In the present embodiment, asshown in FIG. 4, the driving position of the driver 3 is set to aposition where the front end 310 of the driver 3 slightly protrudes fromthe outlet 123. The driving position is also a position where front endsof the arm parts 35 respectively abut from the rear on a pair of frontstopper parts 117 fixed within a front end portion of the body housing11. With the above-described arrangement, in the present embodiment, theinitial position and the driving position can also be respectivelyreferred to as a rearmost position and a foremost position which defineopposite ends of a movable range of the driver 3.

In the present embodiment, as shown in FIG. 2, the driver-drivingmechanism 400 includes a flywheel 4, two ring members 5, a holdingmechanism 6, an actuating mechanism 7 and a pressing mechanism 8. Thestructures of these components are now described in detail in thisorder. It is noted that, in FIGS. 1 and 2 to be referenced below, forconvenience of explanation, the ring member 5 is shown partiallycutaway.

The flywheel 4 has a circular cylindrical shape and is rotatablysupported in front of the motor 2 within the body housing 11, as shownin FIG. 2. The flywheel 4 may be rotationally driven around a rotationaxis A1 by the motor 2. The rotation axis A1 extends in parallel to arotation axis of the motor 2 and in the right-left direction orthogonalto the operation line L of the driver 3. A pulley 41, which isconfigured to rotate together with the flywheel 4, is connected to asupport shaft of the flywheel 4. A belt 25 is looped over the pulleys 21and 41. Therefore, when the motor 2 is driven, rotation of the motor 2is transmitted to the flywheel 4 via the belt 25, and the flywheel 4rotates clockwise as viewed in FIG. 2. Further, as shown in FIGS. 5 and6, a pair of engagement grooves 47 are formed to extend over the wholecircumference of an outer periphery 45 of the flywheel 4. The engagementgrooves 47 are configured to engage with the ring members 5. Each of theengagement grooves 47 is formed such that its width in the right-leftdirection decreases toward the inner side in the radial direction.

As shown in FIG. 2, each of the ring members 5 has a ring-like shapehaving a larger diameter than the flywheel 4. In the present embodiment,the inner radius of the ring member 5 is set to be larger than theradius of the flywheel 4 (strictly, the radius from the rotation axis A1of the flywheel 4 to the bottom of the engagement groove 47). As shownin FIG. 5, the two ring members 5 are disposed radially outside of theengagement grooves 47 formed in the outer periphery 45 of the flywheel4. In the present embodiment, the two ring members 5 are held by theholding mechanism 6, which will be described later, so as to be movablebetween a separate position where the ring member 43 is apart from theouter periphery 45 (more specifically, the engagement groove 47) of theflywheel 4 and a contact position where the ring member 43 is in partialcontact with the outer periphery 45 (the engagement groove 47).

The ring member 5 is a transmitting member for transmitting therotational energy of the flywheel 4 to the driver 3, and configured tobe frictionally engaged with the driver 3 and the flywheel 4. As shownin FIG. 6, an outer peripheral engagement part 51 and an innerperipheral engagement part 53, which are respectively engageable withthe engagement groove 308 of the driver 3 and the engagement groove 411of the flywheel 41, are respectively formed in outer and innerperipheries of the ring member 5. The ring member 5 has a generallyhexagonal cross-section in the radial direction. The outer peripheralengagement part 51 is formed such that its thickness in the axialdirection of the ring member 5 decreases toward the outer side in theradial direction of the ring member 5, and the inner peripheralengagement part 53 is formed such that its thickness in the axialdirection of the ring member 5 decreases toward the inner side in theradial direction of the ring member 5. In other words, both the outerperipheral engagement part 51 and the inner peripheral engagement part53 are formed to have a cross-section tapered toward their respectivetip ends in the radial direction. Engagement between the ring member 5and the driver 3 and the flywheel 4 will be described in detail later.

The holding mechanism 6 is configured to hold the ring member 5 suchthat the ring member 5 is movable between the separate position, inwhich the ring member 43 is apart from the outer periphery 45 of theflywheel 4 (the engagement groove 47), and the contact position, inwhich the ring member 43 is in contact with the outer periphery 45 (theengagement groove 47). As shown in FIGS. 2 and 5, the holding mechanism6 of the present embodiment includes a pair of ring-biasing parts 60 anda pair of stoppers 66. The ring-biasing parts 60 are respectivelydisposed diagonally forward and downward of the ring members 5 anddiagonally rearward and downward of the ring members 5. The ring-biasingparts 60 rotatably support the ring members 5 while biasing the ringmembers 5 upward from below by leaf springs. The stoppers 66 aredisposed below the driver 3 and respectively diagonally forward andupward of the ring members 5 and diagonally rearward and upward of thering members 5. The stoppers 66 are configured to restrict upwardmovement of the ring members 5 while allowing rotation of the ringmembers 5.

The manner of holding the ring members 5 by the holding mechanism 6 isnow described. As shown in FIG. 5, in the initial state, thering-biasing parts 60 abut on the ring members 5 from below to bias thering members 5 upward, while the stoppers 66 abut on the ring members 5from above to prevent the ring members 5 from further moving upward.Thus, as shown in FIG. 6, the ring members 5 are each held in theseparate position apart from the outer periphery 45 (the engagementgroove 47) over the whole circumference of the flywheel 4, although onlyan upper end portion of the flywheel 4 is shown. On the other hand, asthe driver 3 is moved forward by the actuating mechanism 7 and pressesthe ring members 5 downward, the ring members 5 are each moved downwardagainst the biasing force of the ring-biasing parts 60 and held in thecontact position in contact with the outer periphery 45 (the engagementgroove 47) on an upper portion of the flywheel 4 (see FIG. 12), whichwill be described in further detail later.

As shown in FIG. 2, the actuating mechanism 7 is disposed above thedriver 3 and rearward of the flywheel 4 within the body housing 11. Theactuating mechanism 7 is configured to move the driver 3 from theinitial position to a transmitting position to be described later. Inthe present embodiment, the actuating mechanism 7 mainly includes asolenoid 715 and the push-out lever 711 which may be turned by a rod ofthe solenoid 715. In the initial state, a leading end portion of thepush-out lever 711 is held diagonally upward and rearward of thelever-abutting part 305 of the lever 3. When the solenoid 715 isactuated, the push-out lever 711 is turned downward and the leading endportion of the push-out lever 711 pushes the lever-abutting part 305forward from the rear and thereby moves the driver 3 forward (see FIG.11). It is noted that, in the present embodiment, the controller 18 (seeFIG. 1) controls actuation of the solenoid 715, which will be describedin detail later.

As shown in FIG. 2, the pressing mechanism 8 is disposed within the bodyhousing 11 to face the driver 3 on the side opposite to the flywheel 4in a direction in which the flywheel 4 and the driver 3 face with eachother. The pressing mechanism 8 is configured to press the driver 3toward the ring members 5 (that is, toward the flywheel 4) to therebyenable transmission of rotational energy from the flywheel 4 to thedriver 3 via the ring members 5 in the process in which the driver 3moves forward from the initial position.

As shown in FIGS. 2 and 6, in the present embodiment, the pressingmechanism 8 includes a roller support member 81, the pressing rollers83, a holder 85 and an elastic member 87. The pressing rollers 83 arerotatably supported by the roller support member 81. The holder 85 issupported by the body housing 11 and holds the roller support member 81so as to be movable in the up-down direction. The elastic member 87 isdisposed between the roller support member 81 and the holder 85 whilebeing slightly compressed. With such a structure, in the initial state,the roller support member 81 and the pressing rollers 83 are biaseddownward by elastic force of the elastic member 87 and held in alowermost position.

As shown in FIG. 2, the acceleration sensor 115 is disposed within therear end portion of the body housing 11. The acceleration sensor 115 isa well-known sensor which is capable of detecting acceleration, andconfigured to output a detection result to the controller 18 (seeFIG. 1) via wiring (not shown). In the present embodiment, accelerationis used as information corresponding to movement of the tool body 10which is caused by the driving operation. The motor 2 is controlledbased on acceleration detected by the acceleration sensor 115, whichwill be described in detail later.

The internal configuration of the handle 14 is now described.

As shown in FIG. 2, the trigger switch 141 is disposed inside an upperend portion of the handle 14, as described above. The controller 18 ishoused inside a lower end portion of the handle 14 (above the batterymounting part 15). The controller 18 is configured to control operationsof the driver-driving mechanism 400 by controlling the motor 2 and thesolenoid 715. Further, a speed display part 116 is provided on the lowerend portion of the handle 14 (above the controller 18). In the presentembodiment, the speed display part 116 includes three LED lights havingdifferent sizes. The controller 18 (see FIG. 1) controls drive of theLEDs according to the set rotation speed of the motor 2. Specifically,the number, color and driving mode (lighting or blinking) of the LEDs tobe driven may be changed according to the rotation speed of the motor 2.

The electrical configuration of the nailing machine 1 is now described.As shown in FIG. 7, the nailing machine 1 includes the controller 18 forcontrolling operations of the nailing machine 1. In the presentembodiment, the controller 18 is configured as a microcomputer includinga CPU 181, a ROM 182, a RAM 183 and a timer 184.

A three-phase inverter 201 and a Hall sensor 203 are electricallyconnected to the controller 18. In the present embodiment, thethree-phase inverter 201 has a three-phase bridge circuit using sixsemiconductor switching elements. The three-phase inverter 201 isconfigured to drive the motor 2 by switching each of the switchingelements of the three-phase bridge circuit according to the duty ratioindicated by a control signal from the controller 18. The Hall sensor203 includes three Hall elements which are each disposed to correspondto each phase of the motor 2. The Hall sensor 203 is configured tooutput a signal which indicates the rotation position of a rotor of themotor 2. Actual rotation speed of the motor 2 may be obtained from therotation position detected by the Hall sensor 203, so that it can alsobe said that the Hall sensor 203 is configured to detect the rotationspeed of the motor 2. Although described in detail later, in the presentembodiment, the controller 18 (the CPU 181) controls the rotation speedof the motor 2 by changing the duty ratio based on the rotation speed ofthe motor 2 which is detected before and after a driving operation. Thecontroller 18 and the three-phase inverter 201 are mounted on a board180 and housed in the lower end portion of the handle 14 (see FIG. 1).

Further, the contact arm switch 131, the trigger switch 141, thesolenoid 715, the acceleration sensor 115 and the speed display part(LEDs) 116 are electrically connected to the controller 18. In thepresent embodiment, the CPU 181 controls driving of the motor 2 and thesolenoid 715 by appropriately outputting control signals to thethree-phase inverter 201 and the solenoid 715 based on signals outputtedfrom the contact arm switch 131, the trigger switch 141 and theacceleration sensor 115. Further, the CPU 181 controls lighting of thespeed display part (LEDs) 116 according to the rotation speed of themotor 2.

Control of the nailing machine 1 in the present embodiment is nowbriefly described.

First, as described above, performing both operations of pressing thecontact arm 13 and depressing the trigger 140 (regardless of the order)is defined as conditions for starting a driving operation. It is notedhere that a certain amount of time is required after driving of themotor 2 is started, in order to store in the flywheel 4 the rotationalenergy which is sufficient to drive the nail 101 with the driver 3.Therefore, in the present embodiment, in order to establish a state inwhich sufficient rotational energy is already stored in the flywheel 4at the time when the two operations are performed, the two operationsare treated as follows. One of the two operations which is performedfirst is regarded as an input operation for inputting an instruction ofdriving the motor 2 in advance to enter a standby state (hereinafterreferred to as a standby instruction). The other operation which isperformed later is regarded as an input operation for inputting aninstruction of actuating the solenoid 715 (hereinafter referred to as anactuation instruction).

Further, release of the depressing operation of the trigger 140 afterthe two operations are performed (in other words, after a drivingoperation is performed once) is regarded as an input operation forinputting an instruction of cancelling the standby state (hereinafterreferred to as a standby-cancel instruction). On the other hand, theoperation of pressing the contact arm 13 which is performed withoutcancelling the standby state (that is, while the depressing operation ofthe trigger 140 is continued) is regarded as an input operation forinputting a new actuation instruction. In other words, in a case wherethe depressing operation of the trigger 140 is continued and the standbystate is maintained, a next driving operation can be performed inresponse to the operation of pressing the contact arm 13. As a result,rotational energy can be efficiently stored and operability incontinuously driving the nails 101 can be improved.

As described above, in the present embodiment, driving of the motor 2 isstarted and stopped in response to the above-described input operationsfor inputting various instructions. Specifically, the CPU 181 recognizesvarious instructions based on the on/off states of the contact armswitch 131 and the trigger switch 141 and starts or stops driving of themotor 2 according to the instructions.

Further, the inventor of the present application has focused on the factthat certain correspondences exist between the rotational energy of theflywheel 4 before a driving operation and the rotational energy of theflywheel 4 consumed in the driving operation by the driver 3(hereinafter referred to as energy consumption), and the state of thenail 101 driven into the workpiece 100. Here, the energy consumption isa difference between rotational energy of the flywheel 4 before adriving operation (hereinafter referred to as pre-driving energy) androtational energy of the flywheel 4 after the driving operation(hereinafter referred to as post-driving energy). In the presentembodiment, the rotation speed of the motor 2 is set based on thecorrespondences every time a driving operation is actually performed, sothat the rotational energy for a next driving operation is controlled tobe within a range in which the nail 101 can be properly driven into theworkpiece 100.

Specifically, the CPU 181 sets rotation speed N of the motor 2 withreference to a table 187 illustrated in FIG. 8 every time a drivingoperation is performed, and drives the motor 2 at the set rotation speedN. It is noted that the table 187 is stored in advance in the ROM 182(see FIG. 7) of the controller 18.

The table 187 is now described. As shown in FIG. 8, rotation speed N1(rpm: revolutions per minute) of the motor 2 before a driving operation,a range of rotation speed N2 (rpm) of the motor 2 after the drivingoperation, and rotation speed N (rpm) of the motor 2 for a next drivingoperation are associated with each other and stored in the table 187.

The table 187 is prepared based on a driven state of the nail 101 whichis specified for each of several different rotation speeds at which theflywheel 4 is actually rotated. The driven state of the nail 101includes, for example, a proper state, an insufficient state and anexcessive state. The proper state refers to a state in which a head ofthe driven nail 101 is substantially flush with a surface of theworkpiece 100 and corresponds to a case in which energy consumption isproper. The insufficient state refers to a state in which the head ofthe nail 101 protrudes from the surface of the workpiece 100 andcorresponds to a case in which energy consumption is insufficient. Theexcessive state refers to a state in which the head of the nail 101 isburied in the workpiece 100 and corresponds to a case in which energyconsumption is excessive. In a case where the driven state of the nail101 is proper, the rotational energy to be supplied to the driver 3 forthe next driving operation need not be changed. In a case where thedriven state of the nail 101 is insufficient, it is preferred toincrease the rotational energy to be supplied to the driver 3 accordingto the degree of insufficiency. In a case where the driven state of thenail 101 is excessive, it is preferred to reduce the rotational energyto be supplied to the driver 3 according to the degree of excessiveness.

Considering the above, the pre-driving energy can be associated with arange of the post-driving energy which corresponds to the proper state,a range of the post-driving energy which corresponds to the insufficientstate, and a range of the post-driving energy which corresponds to theexcessive state. Further, each of the ranges of the post-driving energycan be associated with the necessity for increase or decrease of therotational energy to be supplied to the driver 3 in the next drivingoperation. It is noted that the ranges of the post-driving energieswhich respectively correspond to the insufficient state and theexcessive state can be further subdivided into a plurality of rangesaccording to the degree of insufficiency and the degree ofexcessiveness, respectively.

When the rotational energy of the flywheel 4 is defined as E (J: joule),the moment of inertia of the flywheel 4 is defined as I (kg·m²: kilogramsquare meter) and the angular velocity of the flywheel 4 is defined as ω(rad/s: radians per second), the rotational energy E can be expressed bythe following equation:E=Iω ²/2

The moment of inertia I of the flywheel 4 is constant, and the angularvelocity ω (rad/s) of the flywheel 4 can be converted into the rotationspeed (rpm). Further, the rotation speed of the flywheel 4 has aproportional relation to the rotation speed of the motor 2 according tothe rotation ratio between the pulleys 21 and 41. Therefore, therotational energy of the flywheel 4 can be expressed as a function ofthe rotation speed of the motor 2. In the present embodiment, in orderto facilitate the processing, the rotation speed N1 of the motor 2before a driving operation is employed as information corresponding tothe pre-driving energy, and the rotation speed N2 of the motor 2 afterthe driving operation is employed as information corresponding to thepost-driving energy. In the present embodiment, in particular, since abrushless motor is employed as the motor 2, the Hall sensor 203 fordetecting the rotation position of the rotor is required, in the firstplace. Therefore, appropriate information can be easily obtained as theinformation corresponding to the pre-driving energy and the post-drivingenergy, by utilizing the rotation speeds N1 and N2 of the motor 2,without the need for providing an additional detecting mechanism.

Increase or reduction of the rotational energy to be supplied to thedriver 3 can be realized by increase or reduction of the rotationalenergy of the flywheel 4, and thus increase or reduction of the rotationspeed of the motor 2, before the next driving operation. Therefore, therange in which the rotational energy to be supplied to the driver 3 neednot be changed is associated with rotation speed N of the motor 2 forthe next driving operation which is the same as the rotation speed N1.The range in which the rotational energy to be supplied to the driver 3needs to be increased is associated with rotation speed N which ishigher than the rotation speed N1. Further, the range in which therotational energy to be supplied to the driver 3 needs to be reduced isassociated with rotation speed N which is lower than the rotation speedN1.

More specifically, for example, in a case where the rotation speed N1 ofthe motor 2 before a driving operation is 12,000 rpm, the rotation speedN2 of the motor 2 after the driving operation in the range of less than7,000 rpm is associated with rotation speed N of 12,000 rpm, which isthe same as the rotation speed N1. In other words, in a case where therotation speed N1 is 12,000 rpm and the rotation speed N2 is less than7,000 rpm, the energy consumption is within a proper range, so that therotation speed N is not changed from that in the previous drivingoperation. In the present embodiment, a maximum speed within a settablerange is 12,000 rpm.

Further, the rotation speed N2 in the range of 7,000 to 8,000 rpm isassociated with the rotation speed N of 11,000 rpm, which is lower thanthe rotation speed N1. Specifically, in a case where the rotation speedN1 is 12,000 rpm and the rotation speed N2 is in the range of 7,000 to8,000 rpm, energy consumption is within a range of the excessive state,so that the rotation speed N is set lower than that in the previousdriving operation, in order to reduce the rotational energy to besupplied to the driver 3. In a case where the rotation speed N2 is inthe range of 8,000 to 9,000 rpm, the energy consumption is within arange of a further excessive state, so that the rotation speed N2 inthis range is associated with further lower rotation speed N of 10,000rpm. The rotation speed N2 in the range of 9,000 rpm or more issimilarly associated with the rotation speed N, although not describedin detail here. In the present embodiment, a minimum speed within thesettable range is 8,000 rpm.

Further, for example, in a case where the rotation speed N1 of the motor2 before a driving operation is 11,000 rpm, the rotation speed N2 of themotor 2 after the driving operation in the range of less than 5,000 rpmis associated with the maximum speed of 12,000 rpm, as the rotationspeed N of the motor 2 for the next driving operation. It is noted that5,000 rpm is a threshold of the rotation speed N2 when the rotationspeed N1 is 11,000 rpm. It is known that the rotation speed of the motor2 significantly decreases when the driven state of the nail 101 issignificantly insufficient. Therefore, when the rotation speed N2 islower than the threshold, the maximum speed is set as the rotation speedN, in order to effectively increase the rotational energy to be suppliedto the driver 3. Although not described in detail, in the rest of thetable 187, the rotation speed N1, the rotation speed N2 and the rotationspeed N are also associated with each other based on similar criteria.

Details of driving control processing to be executed by the CPU 181 ofthe controller 18 and specific operations of the nailing machine 1during this processing are now described with reference to FIGS. 9 and10. The driving control processing is started when the battery 19 ismounted to the battery mounting part 15 and power supply to the nailingmachine 1 is started. The driving control processing is terminated whenthe power supply is stopped. In the following description and drawings,each “step” in the processing is simply expressed as “S”. Further, inthe drawings, the “switch” is also simply expressed as “SW”.

At the start of the driving control processing, the contact arm 13 andthe trigger 140 are both in their initial positions, and the contact armswitch 131 and the trigger switch 141 are both in the off-state. Themotor 2 is in a non-driven state, in which the motor 2 is not yetdriven. As shown in FIG. 1, the driver 3 has been returned to theinitial position by the return mechanism and is held in the initialposition. As shown in FIG. 6, each of the ring members 5 is held by theholding mechanism 6 in the separate position slightly apart radiallyoutward from the outer periphery 45 (more specifically, from theengagement groove 47) of the flywheel 4. At this time, each of thepressing rollers 83 is held in the lowermost position and in slidingcontact with the front end portion of the body 30 of the driver 3 fromabove, but not yet pressing the driver 3 downward. In this state, eachof the ring members 5 is also held in a position apart from the driver3. More specifically, each of the ring members 5 is held in a positionin which the outer peripheral engagement part 51 is slightly apartdownward from the corresponding engagement groove 308 of the driver 3.

As shown in FIG. 9, the CPU 181 first sets an initial value as therotation speed N of the motor 2 (S11). In the present embodiment, theinitial value is a maximum value (maximum speed of 12,000 rpm) withinthe settable range of the rotation speed N. The initial value is storedin advance in the ROM 182, and in S11, the CPU 181 reads out the initialvalue from the ROM 182 and stores the initial value in the RAM 183, asthe rotation speed N of the motor 2 for the next driving operation.

The CPU 181 lights the LEDs of the speed display part 116 according tothe rotation speed N of the motor 2 (S12). At this time, all of thethree LEDs are lighted to indicate that the rotation speed N is set tothe maximum value. Thus, a user can readily recognize the automaticallyset rotation speed N.

The CPU 181 waits until a standby instruction is inputted (S13: NO,S13). When either the contact arm switch 131 or the trigger switch 141is turned on, the CPU 181 recognizes this as an input of the standbyinstruction (S13: YES), and starts driving of the motor 2 (S15).Specifically, the CPU 181 starts energization to the motor 2 via thethree-phase inverter 201. At this time, the CPU 181 controls the dutyratio such that the rotation speed of the rotor of the motor 2 becomesthe rotation speed N stored in the RAM 183. Further, the on/off statesof the trigger switch 141 and the contact arm switch 131 which arerecognized by the controller 18 are stored, for example, when theirrespective corresponding flags are set or cleared in the RAM 183.

When the flywheel 4 is rotationally driven along with driving of themotor 2, storage of the rotational energy is started. At this stage, thering members 5 are each held in the separate position and are thusincapable of transmitting the rotational energy of the flywheel 4 to thedriver 3. Therefore, even if the flywheel 4 rotates, the ring members 5and the driver 3 do not operate.

The CPU 181 continues to monitor until a standby-cancel instruction oran actuation instruction is inputted before a specified time elapsesafter the standby instruction is inputted (S17: NO, S19: NO, S23: NO,S17). The standby-cancel instruction as used herein corresponds toturning off of the contact arm switch 131 or the trigger switch 141,which has been used to input the standby instruction.

In a case where the specified time elapses without an input of thestandby-cancel instruction or the actuation instruction (S17: YES) or ina case where the standby-cancel instruction is inputted within thespecified time (S17: NO, S19: YES), the CPU 181 stops driving of themotor 2 (S21), and returns to monitoring of input of the standbyinstruction (S13). It is noted that whether the specified time haselapsed or not is determined, for example, by counting the elapsed timeafter input of the standby instruction with the timer 184, and comparingthe elapsed time with the specified time stored in advance in the ROM182. The specified time is not particularly limited, but, for example,in the present embodiment, it is set to 5 seconds.

In a case where the actuation instruction is inputted before thespecified time elapses, that is, in a case where the contact arm switch131 or the trigger switch 141 which has not been used to input to thestandby instruction is also turned on (S17: NO, S19: NO, S23: YES), theCPU 181 specifies the rotation speed N1 of the motor 2 before thedriving operation, which is detected by the Hall sensor 203 (see FIG.7), and stores it in the RAM 183 (S25 in FIG. 10). The CPU 181 stopsdriving of the motor 2 (S27) by once stopping energization to the motor2. Although driving of the motor 2 is stopped, the flywheel 4 and therotor of the motor 2 continue to rotate by inertia. Substantially at thesame time when driving of the motor 2 is stopped, the CPU 181 actuatesthe solenoid 715 in response to the actuation instruction, therebycauses the driver 3 to perform a driving operation (S29).

Specifically, the driving operation is performed as follows. First, whenthe solenoid 715 is actuated, the push-out lever 711 turns and theleading end portion of the push-out lever 711 pushes the lever-abuttingpart 305 of the driver 3 forward from the rear. Thus, the driver 3starts moving forward from the initial position toward the drivingposition along the operation line L. The driver 3 also moves relative tothe ring members 5 each held in the separate position.

The pressing rollers 83 abut on the respective abutment surfaces of theinclined parts 302 from the front. As the inclined parts 302 moveforward while being pressed by the pressing rollers 83, a portion of theouter peripheral engagement part 51 of each of the ring members 5 entersthe corresponding engagement groove 308 (see FIG. 6) of the driver 3 andabuts on an open end of the engagement groove 308. Further, with thestructure in which the inclined part 307 is formed in the front endportion of the ring-engagement part 306 and the width of the engagementgroove 308 in the right-left direction increases toward the open end,the outer peripheral engagement part 51 can smoothly enter theengagement groove 308. When the driver 3 further moves forward, whilethe pressing rollers 83 abut on the respective abutment surfaces of theinclined parts 302 and a portion of the outer peripheral engagement part5 abuts on the open end of the corresponding engagement groove 308, eachof the inclined parts 302 functions as a cam and exhibits a wedgeeffect. Therefore, the ring members 5 are each pushed downward from theseparate position against the biasing force of the ring-biasing parts60. At the same time, the pressing rollers 83 are each pushed upwardfrom the lowermost position against the biasing force of the elasticmember 87.

When the driver 3 further moves forward and reaches the transmittingposition shown in FIG. 11, as shown in FIG. 12, a portion of the innerperipheral engagement part 53 of each of the ring members 5 moveddownward enters the corresponding engagement groove 47 of the flywheel 4and abuts on an open end of the engagement groove 47, so that the ringmembers 5 are prevented from further moving downward. At this time, eachof the ring members 5 is rotatably supported in the lowermost positionby the ring-biasing parts 60 while being separated from the stoppers 66,and only a portion of the inner peripheral engagement part 53 abuts onan upper portion of the flywheel 4. Thus, the ring members 5 are eachheld in the contact position by the holding mechanism 6. Further, thering members 5 are pressed against the flywheel 4 via the driver 3 bythe elastic force of the elastic member 87 which is compressed when thepressing rollers 83 are pushed up by the inclined parts 302. Therefore,a portion of the outer peripheral engagement part 51 of each of the ringmembers 5 is frictionally engaged with the driver 3 at the open end ofthe engagement groove 308 of the driver 3, and a portion of the innerperipheral engagement part 53 of each of the ring members 5 isfrictionally engaged with the flywheel 4 at the open end of theengagement groove 47 of the flywheel 4.

Thus, when the ring members 5 are frictionally engaged with the driver 3and the flywheel 4, the driver 3 becomes capable of receiving therotational energy of the flywheel 4 via the ring member 5. Here, a“frictionally engaged state” refers to a state (including a slidingstate) that two members are engaged with each other by friction. Each ofthe ring members 5 is rotated around the rotation axis A2 by theflywheel 4 in a state in which only a portion of the inner peripheralengagement part 53 of the ring member 5 which is pressed against theflywheel 4 by the driver 3 is frictionally engaged with the flywheel 4.Further, in the present embodiment, as shown in FIG. 11, the ring member5 is formed to have a larger diameter than the flywheel 4, and the innerradius of the ring member 5 is set to be larger than the outer radius ofthe flywheel 4 (strictly, the radius from the rotation axis A1 of theflywheel 4 to the bottom of the engagement groove 47). Therefore, therotation axis A2 of the ring member 5 is different from the rotationaxis A1 of the flywheel 4 and extends below the rotation axis A1 (in aposition further apart from the driver 3). Further, the rotation axis A2extends in parallel to the rotation axis A1. The ring members 5 push outthe driver 3 forward from the transmitting position shown in FIG. 11while being frictionally engaged with the driver 3.

When the driver 3 is pushed out forward from the transmitting position,as shown in FIG. 13, each of the pressing rollers 83 abuts on theabutment surface of a portion of the roller-abutting part 301 whichextends rearward from the inclined part 302, and is pushed up to anuppermost position. The ring members 5 are further pressed against theflywheel 4 via the driver 3 by the elastic force of the elastic member87. Therefore, frictional engagements between the driver 3 and a portionof the outer peripheral engagement part 51 and between the flywheel 4and a portion of the inner peripheral engagement part 53 get firmer.Thus, the ring members 5 can more efficiently transmit the rotationalenergy of the flywheel 4 to the driver 3. FIG. 13 shows the state inwhich the driver 3 is placed in a striking position where the driver 3strikes the nail 101 (see FIG. 1). Further, when a specified timerequired for the driver 3 to reach the striking position elapses afteractuation of the solenoid 715 in S29 of the driving control processing(see FIG. 10), the CPU 181 stops supply of current to the solenoid 715to thereby return the push-out lever 711 to the initial position.

The driver 3 reaches the striking position and strikes the nail 101, andfurther moves to the driving position shown in FIG. 4 and drives thenail 101 into the workpiece 100. When front ends of the arm parts 35 ofthe driver 3 abut on the front stopper parts 117 from the rear, movementof the driver 3 is stopped and the driving operation is finished.Accordingly, the return mechanism (not shown) is actuated to return thedriver 3 to the initial position.

As shown in FIG. 10, the CPU 181 actuates the solenoid 715 in S29, andthen when the driving operation of the driver 3 is finished, the CPU 181specifies the rotation speed N2 of the motor 2 after the drivingoperation, which is detected by the Hall sensor 203, and stores therotation speed N2 in the RAM 183 (S31). The timing of specifying therotation speed N2 may be set, for example, according to the timerequired for the driver 3 to move to the driving position and completethe operation of driving the nail 101 after the solenoid 715 isactuated. It is noted that the time required for the driver 3 to move tothe driving position and complete the operation of driving the nail 101is quite short (about 30 milliseconds).

Further, the CPU 181 determines whether or not the acceleration detectedby the acceleration sensor 115 exceeds a specified threshold (S33). Thethreshold of the acceleration is set and stored in advance, for example,in the ROM 182. As describe above, the acceleration is employed as theinformation corresponding to the movement of the tool body 10 which iscaused by the driving operation. In such a case in which the nail 101 ishardly driven into the workpiece 100 and the tool body 10 is reboundedby reaction (typically, moves in a direction away from the workpiecesubstantially in parallel to the operation line L) (specifically, in acase where energy consumption is significantly insufficient), theacceleration increases. Therefore, in a case where the accelerationexceeds the threshold (S33: YES), the CPU 181 sets the initial value(that is, the maximum value within the settable range) as the rotationspeed N, in order to effectively increase the rotational energy to besupplied to the driver 3 (S34).

In a case where the acceleration does not exceed the threshold (S33:NO), the CPU 181 sets the rotation speed N which is associated with therotation speed N1 and the rotation speed N2 with reference to the table187 (S35). In S34 or S35, the rotation speed N stored at this point oftime in the RAM 183 is replaced with a newly set rotation speed N. TheCPU 181 lights the LEDs of the speed display part 116 according to therotation speed N of the motor 2 which is set in S34 or S35 (S36).

The CPU 181 determines whether or not the standby-cancel instruction isinputted (S37). Further, the standby-cancel instruction as used hereincorresponds to turning off of the trigger switch 141. In a case wherethe standby-cancel instruction is inputted (S37: YES), the CPU 181continues to monitor until the standby instruction is inputted (S39: NO,S41: NO, S39) before a specified time elapses after input of thestandby-cancel instruction. The specified time adopted in S39 may be thesame as or different from that in S17. In the present embodiment, it isset to the same 5 seconds as in S17.

In a case where the specified time elapses without input of the standbyinstruction (S39: YES), the CPU 181 returns to the processing of S11 inFIG. 9 and sets the rotation speed N to the initial value. In otherwords, in a case where the standby state is cancelled after the drivingoperation and a new standby instruction is not inputted for thespecified time, the setting of the rotation speed N of the motor 2 isreturned to the maximum speed. The subsequent processing is executed asdescribed above.

In a case where the standby instruction is inputted within the specifiedtime (S39: NO, S41: YES), the CPU 181 returns to the processing of S15in FIG. 9 and starts driving of the motor 2. At this time, the CPU 181controls the rotation speed of the rotor of the motor 2 to become therotation speed N which is set in S34 or S35 after the previous drivingoperation and stored in the RAM 183. The subsequent processing isexecuted as described above.

In a case where the CPU 181 determines that the trigger switch 141 isheld in the on-state and the standby-cancel instruction is not inputted(S37: NO), the CPU 181 starts driving of the motor 2 at the rotationspeed N which is set in S34 or S35 after the previous driving operationand stored in the RAM 183 (S43). This processing is provided so that therotational energy can be stored in the flywheel 4 until an actuationinstruction is inputted, as described above. The CPU 181 continues tomonitor until an actuation instruction is inputted before a specifiedtime elapses after start of driving of the motor 2 (S45: NO, S49: NO,S45). The specified time adopted in S45 may be the same as or differentfrom that in S17 and S39. In the present embodiment, it is set to thesame 5 seconds as in S17 and S39. In a case where the specified timeelapses without input of the actuation instruction (S45: YES), the CPU181 stops driving of the motor 2 and returns to the processing of S11 inFIG. 9 to set the rotation speed N to the initial value. In other words,in a case where a new actuation instruction is not inputted for thespecified time while being kept in the standby state after the drivingoperation, the setting of the rotation speed N of the motor 2 isreturned to the maximum speed. The subsequent processing is executed asdescribed above.

In a case where the actuation instruction is inputted within thespecified time (S45: NO, S49: YES), the CPU 181 returns to S25 to detectthe rotation speed N1 of the motor 2 before the driving operation andstops driving of the motor 2 (S27), and then actuates the solenoid 715to cause the driver 3 to perform the driving operation (S29). In otherwords, in a case where a new actuation instruction is inputted whilebeing kept in the standby state after the driving operation, the nextdriving operation is immediately performed at the rotation speed N whichis appropriately set based on the previous driving operation.

A specific application example of the driving control processing (seeFIGS. 9 and 10) described above is now described with reference to FIG.14. As shown in FIG. 14, firstly, the initial value of the rotationspeed N is set to the maximum speed of 12,000 rpm (S11). In a case wherethe rotation speeds N1 and N2 which are detected before and after afirst driving operation are respectively 12,000 rpm and 10,000 rpm (S25,S31), it indicates an excessive driven state in which the head of thenail 101 is buried in the workpiece 100A. Accordingly, the rotationspeed N for the next driving operation is set to a lower speed of 8,000rpm, with reference to the table 187 (see FIG. 8) (S35). As a result,the rotation speeds N1 and N2 for a second driving operation decrease to8,000 rpm and 5,000 rpm, respectively (S25, S31), so that a properdriven state can be realized in which the head of the nail 101 issubstantially flush with the surface of the workpiece 100A. In thiscase, the rotation speed N for the next driving operation is set to thesame 8,000 rpm as in the previous driving operation, with reference tothe table 187 (S35). In a third driving operation, the proper drivenstate can also be realized and the rotation speed N is set to the same8,000 rpm as in the previous driving operation (S35).

In a case where a fourth driving operation is performed on a workpiece100B which is harder than the workpiece 100A at the set rotation speed Nof 8,000 rpm, and the rotation speeds N1 and N2 are respectively 8,000rpm and 2,000 rpm (S25, S31), it indicates an insufficient driven statein which the head of the nail 101 protrudes from the surface of theworkpiece 100B. Accordingly, the rotation speed N for the next drivingoperation is set to a higher speed of 10,000 rpm, with reference to thetable 187 (S35). As a result, the rotation speeds N1 and N2 for a fifthdriving operation increase to 10,000 rpm and 6,500 rpm, respectively(S25, S31), so that a proper driven state can be realized.

As described above, in the present embodiment, the CPU 181 sets therotation speed N of the motor 2 based on the rotation speed N1 of themotor 2 as the information corresponding to the pre-driving energy andthe rotation speed N2 of the motor 2 as the information corresponding tothe post-driving energy. More specifically, the CPU 181 sets therotation speed N of the motor 2, with reference to the table 187 storedin the ROM 182. In the table 187, the rotation speed N1, the range ofthe rotation speed N2 and the rotation speed N are associated with eachother based on the correspondences between the rotational energy of theflywheel 4 before a driving operation and the energy consumption by thedriving operation which are actually measured, and the correspondingactual state of the nail 101 driven into the workpiece 100. The CPU 181can easily set the rotation speed N with reference to the table 187 andproperly control the rotational energy to be supplied to the driver 3 inthe next driving operation to thereby realize a proper driven state.

In other words, in the nailing machine 1 of the present embodiment, theCPU 181 automatically can set an appropriate rotation speed N for thenext driving operation every time a driving operation is performed.Thus, a user need not manually set the rotation speed of the motor whilechecking the driven state of the nail, so that the working efficiencycan be improved. In addition, an operation member for manually settingthe rotation speed of the motor 2 is not required, so that an extra costincrease can be prevented. Further, for example, the need for settingthe rotation speed of the motor to be excessively high in order toprevent insufficient driving can be eliminated, which may alsocontribute to protection of the motor 2 and the front stopper parts 117,suppression of power consumption and shortening of a start-up time.Particularly, by suppression of power consumption, the nailing machine1, which is powered by the rechargeable battery 119, can increase thenumber of the nails 101 which can be driven on a single charge and thusimprove working efficiency.

Further, in the present embodiment, in a case where the rotation speedN2 of the motor 2 after a driving operation is smaller than a specifiedthreshold which corresponds to the rotation speed N1 of the motor 2before the driving operation, the rotation speed N of the motor 2 is setto the maximum speed. Similarly, in a case where a specified timeelapses without a next driving operation being performed after a drivingoperation, the rotation speed N of the motor 2 is also set to themaximum speed. Further, in a case where the acceleration detected by theacceleration sensor 115 exceeds a specified threshold, the rotationspeed N of the motor 2 is also set to the maximum speed. All of thesecases are considered to correspond to a significantly insufficientdriven state. Therefore, shortage of the rotational energy to besupplied to the driver 3 in the next driving operation can be reliablyprevented by setting the rotation speed N of the motor 2 to a maximumvalue within the settable range.

The above-described embodiment is a mere example and a driving toolaccording to the present disclosure is not limited to the structure ofthe nailing machine 1 of the above-described embodiment. For example,the following modifications or changes may be made. Further, one or moreof these modifications may be employed in combination with the nailingmachine 1 of the above-described embodiment or the claimed invention.

The driving tool may be a tool for driving out a fastener other than thenail 101. For example, the driving tool may be embodied as a tacker or astaple gun which drives out a rivet, pin or staple. Further, the drivingsource of the flywheel 4 is not particularly limited to the motor 2. Forexample, an alternate current (AC) motor may be employed in place of theDC motor.

The CPU 181 may set the rotation speed N for a specified number of timesof the next driving operations every time the specified number of timesof the driving operations are performed, instead of setting it for eachdriving operation. In this case, the rotation speed N may be set basedon, for example, an average value of the rotation speed N2.

As the information corresponding to the pre-driving energy and theinformation corresponding to the post-driving energy, for example, therotation speeds of the flywheel 4 which are respectively detected beforeand after a driving operation may be employed, in place of the rotationspeeds N1 and N2 of the motor 2. In this case, the rotation speed of theflywheel 4 may be detected, for example, by using a Hall sensor like inthe above-described embodiment. The rotation speed of the motor 2 or theflywheel 4 may be detected by a sensor (such as an optical sensor and acontact type sensor) other than the Hall sensor.

Numerical values of the table 187 shown in FIG. 8 are mere examples forexplaining the correspondences between the rotation speed N1, therotation speed N2 and the rotation speed N. Therefore, as a matter ofcourse, proper numerical values may be appropriately employed accordingto the specifications of the flywheel 4, for example. Further, thecorrespondences between the rotation speed N1, the rotation speed N2 andthe rotation speed N may be stored in a form other than the table 187.Further, the table 187 may be stored in a nonvolatile memory if thenailing machine 1 includes a nonvolatile memory, or in an external,computer-readable storage medium (such as an SD card and a USB memory).The rotation speed N need not necessarily be set with reference to thecorrespondences stored in advance in the table 187 or the like, and maybe calculated based on information corresponding to the pre-drivingenergy and information corresponding to the post-driving energy everytime a driving operation is performed.

In the above-described embodiment, turning on both the contact armswitch 131 and the trigger switch 141 regardless of the order is definedas conditions for starting a driving operation. However, the order ofturning on the two switches may be defined as the conditions forstarting a driving operation. Further, a plurality of operation modeswhich are different in conditions for starting a driving operation maybe provided and the CPU 181 may determine whether to start the drivingoperation according to one of the modes which is selected by a user.

In the above-described embodiment, the CPU 181 sets the rotation speed Nbased on not only the information corresponding to the pre-drivingenergy and the information corresponding to the post-driving energy, butalso the detection result of the acceleration sensor 115. However, theacceleration sensor 115 may be omitted.

The method of indicating to a user the rotation speed N which isautomatically set by the CPU 181 is not limited to the speed displaypart 116 including the LEDs, but any method may be adopted. For example,a numerical value indicating the rotation speed N may be displayed on aliquid crystal display (LCD), or it may be indicated by sound such as abuzzer. Information relating to a driving condition of the motor 2 whichis different from the rotation speed N may be indicated. For example,change of the rotation speed N may be indicated by blinking of the LEDs.Further, for example, in a case where the rotation speed N2 of the motor2 after a driving operation is smaller than a threshold, in a case wherea specified time elapses without a next driving operation beingperformed after a driving operation, or in a case where the accelerationexceeds a specified threshold, an indication that the rotation speed Nof the motor 2 has been reset to the maximum speed may be made bylighting of the LEDs having a color different from that in a normalindication of the rotation speed N. Moreover, not only the drivingcondition of the motor 2 but also other information relating to theoperation state of the nailing machine 1 may be indicated. For example,information corresponding to the detection result of the accelerationsensor 115 (for example, the fact that the acceleration exceeds thethreshold) may be indicated. Further, indication of such informationneed not necessarily be performed.

In the above-described embodiment, as an example, the controller 18 isformed by a microcomputer including the CPU 181, but it may be formed bya programmable logic device such as ASIC (Application SpecificIntegrated Circuits) and FPGA (Field Programmable Gate Array). Further,in order to realize the driving control processing of theabove-described embodiment, the CPU 181 may execute a program stored inthe ROM 182. In a case where the nailing machine 1 includes anonvolatile memory, the program may be stored in the nonvolatile memory.Alternatively, the program may be stored in an external,computer-readable storage medium (such as an SD card and a USB memory).The driving control processing of the above-described embodiment and itsmodifications may be distributed to a plurality of control circuits.

The shape of the driver 3 and the structure of the driver-drivingmechanism 400 for driving the driver 3 may be appropriately changed. Forexample, in each of the roller-abutting parts 301 of the driver 3, theinclined part 302 may have a linear shape as a whole or have a gentlecircular arc shape at least in part when viewed from the side.Specifically, the upper surface (the contact surface with the pressingroller 83) of the inclined part 302 may be a flat or curved surface as awhole, or may by partially flat and partially curved. Further, thedegree of inclination of the inclined part 302 may be changed in themiddle. The inclined part 302 may be formed longer. Each of theroller-abutting part 301 may include a plurality of inclined parts eachhaving a thickness gradually increasing toward the rear. Further, inplace of the driver-driving mechanism 400, a driving mechanism may beadopted which is configured to directly transmit rotational energy fromthe flywheel 4 to the driver 3 by frictionally engaging the driver 3with the flywheel 4, without using the ring members 5. The rotationalenergy of the flywheel 4 may be transmitted to the driver 3 via atransmitting member (for example, an intermediate roller) which isdifferent from the ring members 5.

Engagement of the ring members 5 with the driver 3 and the flywheel 4 isnot limited to the engagement exemplified in the above-describedembodiment. For example, the number of the ring members 5 and thenumbers of the engagement grooves 308 of the driver 3 and the engagementgrooves 47 of the flywheel 4 which correspond to the ring members 5 maybe one, or three or more. Further, for example, the shapes,arrangements, numbers and engaging positions of the outer peripheralengagement part 51 and the inner peripheral engagement part 53 and thecorresponding engagement grooves 308 and 47 may be appropriatelychanged.

The structure of the actuating mechanism 7 may be appropriately changedor modified, as long as the actuating mechanism 7 is configured to movethe driver 3 from the initial state in which the driver 3 is placed inthe initial position to a state in which the rotational energy of theflywheel 4 can be transmitted to the driver 3. For example, theactuating mechanism 7 may be configured such that the flywheel 4 and thedriver 3 are frictionally engaged with each other directly or indirectly(for example, via the ring members 5) by biasing the driver 3 placed inthe initial position toward the flywheel 4, instead of by pushing outthe driver 3 forward toward the transmitting position.

Correspondences between the features of the embodiment and the featuresof the invention are as follows. The nailing machine 1 is an examplethat corresponds to the “driving tool”. The nail 101 is an example thatcorresponds to the “fastener”. The outlet 123 is an example thatcorresponds to the “outlet”. The motor 2 is an example that correspondsto the “motor”. The flywheel 4 is an example that corresponds to the“flywheel”. The driver 3 is an example that corresponds to the “driver”.The operation line L is an example that corresponds to the “operationline”. The CPU 181 is an example that corresponds to the “control part”.The rotation speeds N1 and N2 are examples that correspond to the “firstinformation” and the “second information”, respectively. The ROM 182 isan example that corresponds to the “storage part”. The Hall sensor 203is an example that corresponds to the “first sensor”. The accelerationsensor 115 is an example that corresponds to the “second sensor”. Thespeed display part 116 is an example that corresponds to the “indicationpart”.

In view of the nature of the present disclosure and the above-describedembodiment, the following features (aspects) are provided. One or moreof the following features may be employed separately or in combinationwith any one of the nailing machine 1 of the above-described embodimentand modification thereto, and the claimed invention.

(Aspect 1)

The first information, the second information and the rotation speed ofthe motor are associated with each other and stored in a table inadvance, and the table is stored in a storage part, and

the control part is configured to set the rotation speed with referenceto the table.

(Aspect 2)

The motor is a brushless motor, and

the first sensor comprises a Hall sensor configured to detect a rotationposition of the motor.

(Aspect 3)

The driving tool further comprises a battery mounting part to which arechargeable battery is removably mounted.

(Aspect 4)

The second sensor is provided in a tool body which houses at least themotor and the flywheel, or in a handle connected to the tool body.

(Aspect 5)

The second sensor is an acceleration sensor, and

the control part is configured to set the rotation speed of the motor toa maximum value within a settable range in a case where the accelerationexceeds a specified threshold.

DESCRIPTION OF NUMERALS

1: nailing machine, 10: tool body, 11: body housing, 115: accelerationsensor, 116: speed display part, 117: front stopper part, 118: rearstopper part, 12: nose part, 123: outlet, 13: contact arm, 131: contactarm switch, 14: handle, 140: trigger, 141: trigger switch, 15: batterymounting part, 17: magazine, 18: controller, 180: board, 181: CPU, 182:ROM, 183: RAM, 184: timer, 187: table, 19: battery, 2: motor, 201:three-phase inverter, 203: Hall sensor, 21: pulley, 25: belt, 3: driver,30: body, 301: roller-abutting part, 302: inclined part, 305:lever-abutting part, 306: ring-engagement part, 307: inclined part, 308:engagement groove, 310: front end, 31: striking part, 32: rear end, 35:arm part, 400: driver-driving mechanism, 4: flywheel, 41: pulley, 45:outer periphery, 47: engagement groove, 5: ring member, 51: outerperipheral engagement part, 53: inner peripheral engagement part, 6:holding mechanism, 60: ring-biasing part, 66: stopper, 7: actuatingmechanism, 711: push-out lever, 715: solenoid, 8: pressing mechanism,81: roller support member, 83: pressing roller, 85: holder, 87: elasticmember, 100, 100A, 100B: workpiece, 101: nail, A1: rotation axis, A2:rotation axis

What is claimed is:
 1. A driving tool configured to eject a fastenerfrom an outlet to drive the fastener into a workpiece, the driving toolcomprising: a motor; a flywheel configured to be rotationally driven bythe motor; a driver disposed to face an outer periphery of the flywheeland configured to perform a driving operation of driving the fastenerinto the workpiece by moving along an operation line, by rotationalenergy transmitted from the flywheel; and a control part configured tocontrol driving of the motor, wherein: the control part is configured toset rotation speed of the motor for a subsequent driving operation ofthe driver based on first information and second information of thedriving operation, the first information corresponding to rotationalenergy of the flywheel immediately before the driving operation of thedriver and the second information corresponding to rotational energy ofthe flywheel immediately after the driving operation of the driver. 2.The driving tool as defined in claim 1, wherein the control part isconfigured to set the rotation speed of the motor with reference tocorrespondences between the first information, the second informationand the rotation speed of the motor which are preset and stored in astorage part.
 3. The driving tool as defined in claim 2, wherein: thefirst information, the second information and the rotation speed of themotor are associated with each other and stored in a table in advance,the table is stored in the storage part, and the control part isconfigured to set the rotation speed with reference to the table.
 4. Thedriving tool as defined in claim 1, further comprising: a first sensorconfigured to detect rotation speed of the motor or the flywheel,wherein: the first information is rotation speed of the motor or theflywheel detected by the first sensor before the driving operation, andthe second information is rotation speed of the motor or the flywheeldetected by the first sensor after the driving operation.
 5. The drivingtool as defined in claim 4, wherein: the motor is a brushless motor, andthe first sensor comprises a Hall sensor configured to detect a rotationposition of the motor.
 6. The driving tool as defined in claim 4,wherein the control part is configured to set the rotation speed of themotor to a maximum value within a settable range in a case where therotation speed of the motor or the flywheel detected after the drivingoperation is smaller than a specified threshold.
 7. The driving tool asdefined in claim 1, wherein the control part is configured to set therotation speed of the motor to a maximum value within a settable rangein a case where a specified time elapses without a next drivingoperation being performed after a driving operation.
 8. The driving toolas defined in claim 1, further comprising: a second sensor configured todetect information corresponding to movement of the driving tool causedby the driving operation, wherein: the control part is configured to setthe rotation speed of the motor based on a detection result of thesecond sensor.
 9. The driving tool as defined in claim 8, wherein thesecond sensor is provided in a tool body which houses at least the motorand the flywheel, or in a handle connected to the tool body.
 10. Thedriving tool as defined in claim 8, wherein: the second sensor is anacceleration sensor, and the control part is configured to set therotation speed of the motor to a maximum value within a settable rangein a case where the acceleration exceeds a specified threshold.
 11. Thedriving tool as defined in claim 1, further comprising an indicationpart configured to indicate information relating to a condition ofdriving the motor by the control part.
 12. The driving tool as definedin claim 1, further comprising a battery mounting part configured toremovably receive a rechargeable battery.